JP4413031B2 - Beam position monitor and beam position measuring method - Google Patents

Description

  The present invention relates to a beam position monitor and a beam position measuring method for measuring the position of a beam having high energy such as ultraviolet rays, X-rays, and accelerated particles, and more particularly to a beam position monitor and a beam position measuring method using a diamond film.

  Recently, an excimer laser that generates an ultraviolet laser beam with a short wavelength has been used for microfabrication of a semiconductor to form a fine pattern, and a method for easily measuring the center position of the beam in a short time is required. It has been. In addition, with the increase in the spatial resolution of a microscope, ultraviolet light is used as a light source for a microscope, and a method for easily measuring ultraviolet light in a short time is required for alignment of the optical axis. . Furthermore, in the research in the medical field and the material field, the general use of synchrotron radiation equipment that generates beam-like ultraviolet rays and X-rays and accelerator equipment for elementary particle research is being considered. In such equipment, it is important to accurately measure the beam position, and similar demands are increasing in these fields. However, since high energy beams such as ultraviolet rays, X-rays, and accelerated particles cannot be confirmed with the naked eye, it takes a long time to adjust the optical system and the beam system, which may adversely affect the human body.

Conventionally, a position detection element (PSD: Position Sensitive Detector) using a semiconductor or the like is used for measuring the position of a laser beam (for example, see Patent Document 1). FIG. 9 is a perspective view schematically showing a conventional PSD, and FIG. 10 is an exploded perspective view showing the PSD described in Patent Document 1. As shown in FIG. As shown in FIG. 9, in a conventional PSD, a plurality of strip-shaped first resistance layers 111 are formed in parallel to each other on one surface of a compound semiconductor substrate 110 made of CdTe or HgI ₂ or the like. On the other surface of the compound semiconductor substrate 110, a plurality of strip-shaped second resistance layers 112 extending in a direction perpendicular to the direction in which the first resistance layer 111 extends are formed in parallel to each other. Yes. Then, the electric charges taken out from one end of each resistance layer are divided by the resistance networks 113 and 114, led to two amplifiers in both the x direction and the y direction, and position information is obtained from the output difference.

  On the other hand, the PSD described in Patent Document 1 shown in FIG. 10 has a plurality of signals arranged in a matrix on the other surface, with a common bias electrode 115 provided on one surface of the compound semiconductor substrate 110. An extraction electrode 116 is provided. The signal extraction electrode 116 is connected to an amplifier 117 provided for each row and for each column via a substrate 118 on which a field effect transistor (FET) is formed. . In this PSD, when a laser beam such as radiation is incident, a charge is generated on the surface of the compound semiconductor substrate 110, and the signal is output from the signal extraction electrode 116 to the amplifier 117 to calculate the incident position of the laser beam. .

  However, when the conventional PSD having such a configuration is applied to position measurement of a high energy beam, there are the following problems. The first problem is that when a conventional PSD monitors a high energy beam for a long time, the beam damage increases, the sensitivity of the detection unit is deteriorated, or destruction due to heat generation is caused. Such a problem is particularly serious in a synchrotron radiation facility that generates extremely strong light from the ultraviolet region to the X-ray region. Furthermore, the second problem is that the PSD described in the above-mentioned Patent Document 1 must be provided with a circuit portion for dividing the output in the vicinity of the measurement region, so that the circuit may be damaged by the high energy beam. That is.

  In order to solve the above-described problems, a position monitor using a diamond film having excellent durability against radiation and ultraviolet rays has been proposed (see, for example, Patent Document 2 and Non-Patent Document 1). The ultraviolet position monitor described in Non-Patent Document 1 is based on an ultraviolet sensor using a conventional diamond thin film, and a plurality of detection electrodes are formed on a high resistance diamond. This ultraviolet ray position monitor detects the beam position by measuring and comparing the output from each electrode.

  The radiation light position monitor described in Patent Document 2 is a position monitor that measures the position of the radiation light based on the same principle as that of the conventional PSD using the semiconductor described above. FIG. 11A is a plan view showing the structure of the synchrotron radiation position monitor described in Patent Document 2, and FIG. 11B is a cross-sectional view thereof. As shown in FIGS. 11A and 11B, this synchrotron radiation position monitor is provided with a hole 102 in the center of a disk-shaped diamond plate 101, and an outer periphery from the hole 102 on both sides of the diamond plate 101. Four fan-shaped diamond electrodes 104 made of a semiconductor diamond film are formed on each side toward the portion. The diamond electrodes 104 are arranged at positions facing each other across the diamond plate 101, and a metal electrode 103 is formed on the surface of each diamond electrode 104. That is, four pairs of diamond electrodes 104 and four pairs of metal electrodes 103 are formed on the diamond plate 101.

  In the synchrotron radiation monitor described in Patent Document 2 configured as described above, when measuring the position of the synchrotron radiation, the surface of the diamond plate 101 is perpendicular to the emission direction of the synchrotron radiation and the synchrotron radiation is in the hole 102. Arranged to pass through. The center of the cross section of the emitted light is strongest, and the light intensity decreases as the distance from the center increases. Therefore, the central portion having high intensity passes through the hole 102 and the peripheral portion having low intensity is irradiated onto the diamond plate 101. As a result, a large number of electrons and holes are generated in the region of the diamond plate 101 irradiated with the emitted light, and these electrons and holes are collected on the diamond electrode 104. Therefore, by measuring the current flowing through the metal electrode 103 provided on each diamond electrode 104, the intensity of the emitted light can be measured. Further, when the radiated light has a shape spreading in a point-symmetric manner around the position where the light intensity is strongest, the center of gravity is determined from the distribution of current flowing through the diamond electrode 104 provided on the front surface side and the back surface side of the diamond plate 101 By calculating the position, the center position of the emitted light can be detected.

Japanese Patent No. 2621159 JP-A-8-297166 S. P. Lansley, 6 others, “Imaging deep UV with diamond-base systems”, “Diamond and Related Materials”, 2002, Vol. 11, p. 433-436

  However, when the above-described conventional position monitor for ultraviolet light or radiation light is used to detect the center position of a beam such as ultraviolet light or soft X-ray, there are the following problems. That is, since the conventional ultraviolet position monitor described in Non-Patent Document 1 requires wiring for each electrode, a considerable number of wirings are required to improve the position detection resolution, which is not realistic. In addition, this UV position monitor estimates the position based on the signals obtained from each electrode, so if there is a difference in the sensitivity of each detector due to non-uniformity of the diamond, the output value will vary and errors will occur. Cause.

  In addition, the conventional radiation position monitor described in Patent Document 2 measures the photovoltaic force flowing between the diamond electrodes 104 facing each other across the diamond plate 101 in order to detect the center position of the beam. The sensitivity of the monitor to the beam is affected by the diamond quality of the measurement section. For this reason, if the film quality of the diamond plate on which electrons and holes are generated is non-uniform, spatial variations will occur, and the output from each electrode will not be equal even if the beam is irradiated symmetrically to the position monitor. There is.

  Further, the conventional beam position measurement method can measure a beam irradiated from a light source having a sufficiently large diameter, such as the primary side of the emitted light, but such as a light source for a processing excimer laser and an ultraviolet microscope. In addition, when measuring the collected ultraviolet light source, there is a problem that the position cannot be obtained by calculation because a beam is irradiated to only one electrode and a signal is output from only one electrode. This problem can be solved by increasing the number of electrode pairs and improving the position resolution, but for that purpose, as many signal extraction lines and signal amplification preamplifiers as the number of electrode pairs are required. Not realistic.

  Furthermore, when the position of the radiated light or the like is specified by a conventional position monitor, a pair of electrodes must be arranged at positions symmetrical with respect to the beam in one direction. For example, in the case of positioning in two directions of the X direction and the Y direction perpendicular to each other, two sets of electrode pairs facing each other must be arranged around the beam, and the four directions around the beam are determined by the position monitor. Blocked. As a result, the effective portion of the beam decreases, and the area on which the beam is irradiated to the position monitor increases, and the position monitor tends to cause abnormal heating.

  The present invention has been made in view of such problems, and can measure the center position of a high-energy beam such as high-power radiation light, excimer laser light, and X-ray with high accuracy, and is stable for a long time. It is an object of the present invention to provide a beam position monitor and a beam position measuring method which can be operated at a lower cost than conventional products.

  The beam position monitor according to the first invention of the present application includes a first diamond layer, a surface electrode group including a plurality of surface electrodes formed on one surface of the first diamond layer and arranged in one direction, One diamond layer is formed on one surface and is in contact with and electrically connected to one end of each surface electrode. The resistance is lower than that of the first diamond layer and higher than that of the surface electrode. A second diamond layer; first and second signal extraction electrodes respectively connected to both ends in the one direction of the second diamond layer; and at least the other surface of the first diamond layer A back electrode formed in a region opposite to a region where the surface electrode group is formed, and applying the potential to the surface electrode group via the second diamond layer, the surface electrode group and the back surface And a bias power source for applying a bias voltage between the electrodes, and carriers generated by the beam incident on the first diamond layer are collected by the surface electrode and pass through the second diamond layer. The first and second signal extraction electrodes flow separately.

  In the present invention, the carriers collected by the surface electrode flow to the second diamond layer as a photocurrent, and the photocurrent flows from the position where the second diamond layer is reached to the first and second signal extraction electrodes. Is divided in inverse proportion to the distance up to and flows through the first and second signal extraction electrodes, respectively. Thereby, the difference between the current values output from the first and second signal extraction electrodes or the sum of the current values output from the first and second signal extraction electrodes (total output current value). Since the incident position of the beam can be obtained from the ratio of the current values output from the first or second signal extraction electrode, it is necessary to provide a large number of signal extraction electrodes as in the conventional beam position monitor. And the structure can be simplified. As a result, a highly accurate beam position monitor can be manufactured at low cost. Further, the beam position monitor of the present invention has excellent durability because the detection part is formed of diamond, and can be applied to measurement of a high energy beam.

  The surface electrode group can be composed of a plurality of strip electrodes having the same length and width and parallel to each other. Note that the length and width of the strip electrodes are substantially equal, and some variation in length and width is allowed. Moreover, the length and width of each strip-shaped electrode should just be substantially equal at least in the detection region. Alternatively, the surface electrode may be, for example, a comb shape or a fishbone type. In this way, by forming a large number of narrow electrodes on the detection unit, it is possible to prevent a decrease in the amount of beam incident on the detection unit and improve the detection accuracy of the beam position.

  In addition, a third signal extraction electrode connected to the back electrode may be formed on the other surface of the first diamond layer. Alternatively, the back electrode may be a low resistance silicon substrate, and the high resistance diamond layer may be formed on the low resistance silicon substrate. Thereby, since a manufacturing process can be reduced, manufacturing cost can be reduced.

  Furthermore, the first diamond layer can be formed of polycrystalline diamond synthesized in a gas phase. In that case, the surface of the first diamond layer is covered with a (001) plane, the crystal grains are oriented in a uniaxial direction perpendicular to the substrate surface, and the crystal plane is oriented even in the plane. It is preferable that it is a property diamond layer. Since this highly oriented diamond layer has a smaller crystal defect density near the surface than a general polycrystalline film, the carrier mobility is large, and the detection performance is improved as compared with a conventional beam position monitor.

  Furthermore, the second diamond layer may be formed of vapor-phase synthesized polycrystalline diamond. In that case, the second diamond layer is preferably formed of p-type semiconductor diamond to which boron is added. Thereby, the diamond layer excellent in controllability can be manufactured stably.

The beam position measuring method according to the second invention of the present application includes a surface electrode group composed of a plurality of surface electrodes formed so as to be arranged in one direction on one surface of the first diamond layer, and the first diamond layer. A step of applying a bias voltage to at least the back surface electrode formed in a region opposite to the region where the surface electrode group is formed on the other surface; and a beam incident on the first diamond layer The generated carriers are collected by the surface electrode group by the bias voltage, and are electrically connected in contact with one end of each surface electrode and have a lower resistance than the first diamond layer and the surface electrode. A process of outputting from the first and second signal extraction electrodes connected to both ends in the one direction of the second diamond layer via the second diamond layer having higher resistance than the second diamond layer. If, having the steps of determining the position of incidence of the beam on the basis of the current value I ₂ which is output from the first current value I ₁ which is output from the signal extraction electrodes and second signal extraction electrodes It is characterized by.

In the present invention, the photocurrent divided in the second diamond layer, that is, the current value I ₁ output from the first signal extraction electrode and the current value I ₂ output from the second signal extraction electrode. Therefore, the incident position of the beam can be accurately measured without providing a large number of signal extraction electrodes. For example, when the absolute value of the signal does not matter, such as when specifying the center position of the beam, the current value I ₁ output from the first signal extraction electrode and the second signal extraction electrode are extracted. by the difference between the current value I ₂ which is moved beam or monitor so that 0, it is possible to measure the center position of the beam.

In the step of determining the incident position of the beam, in the step of determining the incident position of the beam, the first relative to the total current value I ₀ (= I ₁ + I ₂ ) output from the first and second signal extraction electrodes. The ratio (I ₁ / I ₀ ) of the current value I ₁ output from one signal extraction electrode, or the ratio of the current value I ₂ output from the second signal extraction electrode to the total current value I ₀ It is preferable to obtain the incident position of the beam from (I ₂ / I ₀ ). As a result, the film quality of the first diamond layer and / or the second diamond layer is not uniform, and the sum of the current values output from the signal extraction electrodes, that is, the total current value I ₀ is the incident light of the measurement light. Even when the position varies, the incident position of the beam can be accurately measured.

  According to the present invention, since the detection layer is formed of diamond, the durability can be improved, and the carrier collected by the surface electrode passes through the diamond layer having higher resistance than the surface electrode. Since the signal is output from the signal extraction electrodes connected to both ends of the layer, the structure can be simplified, and a highly accurate beam position monitor can be manufactured at low cost.

  Hereinafter, a beam position monitor according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing a beam position monitor according to an embodiment of the present invention. As shown in FIG. 1, in the beam position monitor of the present embodiment, a plurality of strip-like electrodes 2 a having the same width and length are formed on one surface of the high-resistance diamond layer 1 as the surface electrode group 2. A low resistance diamond layer 4 is formed around one end of the strip-shaped electrode 2a so as to engage with the end. Thereby, the low resistance diamond layer 4 is electrically connected to the surface electrode group 2. The low resistance diamond layer 4 has a lower resistance than the high resistance diamond layer 1 and a higher resistance than the surface electrode group 2. On the other hand, on the other surface of the high resistance diamond layer 1, a back electrode 3 is formed at least in a region opposite to the region where the surface electrode group 2 is formed. The portion sandwiched between the front electrode group 2 and the back electrode 3 in the high-resistance diamond layer 1 and its peripheral portion serve as a beam detector 6.

  Further, on one surface of the high-resistance diamond layer 1, a pair of low-resistance diamond layers 4 connected to both ends in the arrangement direction of the strip-shaped electrodes 2a and outputting a signal from the low-resistance diamond layer 4 is provided. Signal extraction electrodes 5a and 5b are formed. On the other hand, a signal extraction electrode connected to the back electrode 3 is provided on the other surface of the high resistance diamond layer 1. In addition, the back surface electrode 3 may serve as the signal extraction electrode on the other surface side.

  The high resistance diamond layer 1 and the low resistance diamond layer 4 in the beam position monitor of the present embodiment can be formed by a known method. In particular, the controllability is excellent, and a diamond film can be manufactured stably at a low cost. It is industrially preferable that it is a polycrystalline diamond film synthesized by a vapor phase chemical vapor deposition (CVD) method using plasma. In general, vapor-phase synthesized diamond is polycrystalline, but the high-resistance diamond layer 1 has a surface formed by a (001) plane of diamond, and crystal grains are oriented in a uniaxial direction perpendicular to the substrate surface. More preferably, it is a highly oriented diamond film in which the crystal plane is oriented even in the plane. Although this highly oriented diamond film is broadly classified as a polycrystalline film, the growth direction and in-plane direction of crystal grains are both oriented in a certain direction, and the surface is characterized by a flat (001) facet. Since the surface form is adopted, the crystal defect density in the vicinity of the surface is smaller than that of a normal polycrystalline film. For this reason, carrier mobility is about one digit larger, and good detection characteristics can be obtained.

  FIG. 2A is a cross-sectional view schematically showing crystal grains of a highly oriented diamond film, and FIGS. 2B and 2C are plan views thereof. As shown in FIG. 2A, in the highly oriented diamond film, diamond crystal grains 9 are oriented in a uniaxial direction (z direction) perpendicular to the surface of the substrate 10. In this case, the upper surface (xy plane) of the crystal grain 9 is covered with the (001) plane, but may be oriented in any direction. For example, as shown in FIG. 2B, when the orientations of the xy planes of the crystal particles 9 are different, there is a possibility that the flow of electricity is hindered at the boundary, that is, the crystal grain boundary. Therefore, in the beam position monitor of the present embodiment, as shown in FIG. 2C, a highly oriented diamond film in which the crystal grains 9 are aligned in-plane and the directions of the xy plane are aligned is used.

The specific resistance of the high-resistance diamond layer 1 is not particularly limited, but is preferably 10 ⁹ Ωcm or more, and the leak current is 10 ¹¹ Ωcm or more that is less than the pA level measurable with a normal picoammeter. It is more preferable that

The low-resistance diamond layer 4 can be formed of diamond imparted with conductivity by a known method such as ion implantation or doping. In particular, the low-resistance diamond layer 4 is a p-type synthesized by vapor phase using a gas containing B. Preferably, it is formed of semiconductor diamond. The specific resistance is preferably lower than that of the high-resistance diamond layer 1 and higher than that of the surface electrode group 2. In this case, the optimum value of the doping concentration of B varies depending on the bias voltage and the photocurrent obtained by light irradiation, but the value obtained by dividing the bias voltage by the resistance value at both ends of the low resistance diamond layer 4 is greater than the generated photocurrent. Is preferably 1 × 10 ¹⁶ cm ⁻³ or more, and more preferably 1 × 10 ¹⁹ cm ⁻³ or less where the activation energy of B starts to decrease. The doping concentration of B is more preferably 1 × 10 ^{18 to} 1 × 10 ¹⁹ cm ⁻³ . On the other hand, as a method for selectively forming the low resistance diamond layer 4 on the high resistance diamond layer 1, for example, a known method such as a selective growth method or an etching method can be used.

Furthermore, each electrode such as the front electrode group 2, the back electrode 3, and the signal extraction electrode can be formed of a general metal such as gold, platinum, or aluminum. Alternatively, it may be formed of a very low resistance conductive diamond doped with impurities such as B at a very high concentration. In particular, the surface electrode group 2 preferably has a sufficiently low resistance compared to the low-resistance diamond layer 4, and is formed of conductive diamond having a metal or B doping concentration of 1 × 10 ¹⁹ cm ⁻³ or more. Is preferred. In the case where the surface electrode group 2 is formed of conductive diamond doped with B, the doping concentration of B is more preferably 3 × 10 ²⁰ cm ⁻³ or more. As the formation method, for example, a known method such as a vacuum deposition method, a sputtering method, an ion plating method, or a CVD method can be used.

  Furthermore, a low-resistance silicon substrate may be used as the substrate for forming the high-resistance diamond layer 1, and this low-resistance silicon substrate may be used as the back surface 3. Thereby, the number of manufacturing processes can be reduced and cost can be reduced. When forming a highly oriented diamond film as the high resistance diamond layer 1 on the low resistance silicon substrate, it is preferable to use a low resistance silicon substrate having a (001) surface.

  In the beam position monitor of this embodiment, a plurality of strip electrodes 2 having the same width and length are formed as the surface electrode group 2 in parallel with each other at substantially equal intervals. However, the present invention is not limited to this. For example, an arbitrary shape such as a dot shape can be applied. FIG. 3A is a plan view showing a beam position monitor of a first modification of the present embodiment, and FIG. 3B is a plan view showing the electrode shape. FIG. 4A is a plan view showing a beam position monitor of a second modification of the present embodiment, and FIG. 4B is a plan view showing the electrode shape. When measuring ultraviolet rays and particle beams whose absorption at the electrodes cannot be ignored, it is preferable that the plurality of surface electrodes constituting the surface electrode group have a shape that does not block the energy of the incident beam as much as possible. It is preferable that the shape is constituted by a main electrode and an auxiliary electrode having a narrower width than the main electrode, such as a comb shape shown in b) and a staggered type (fishbone type) shown in FIG. For example, in the beam position monitor of the first modified example of the present embodiment shown in FIG. 3A, the surface electrode group 7 is composed of a plurality of comb electrodes 7a, not strip electrodes. In the beam position monitor of the second modification of the present embodiment shown in FIG. 4A, the surface electrode group 8 is composed of a plurality of fishbone electrodes 8a. By making the surface electrode in such a shape, excellent electrical conductivity can be obtained without reducing the irradiation area. The configuration other than the surface electrode group in the beam position monitor of the first and second modifications is the same as that of the beam position monitor shown in FIG.

  Next, the operation of the beam position monitor of the present embodiment configured as described above, that is, a method of measuring the beam position using the beam position monitor of the present embodiment will be described. First, the surface on which the surface electrode group 2 is formed is used as a light receiving surface, and a beam position monitor is arranged so that the beam is incident on the detection unit 6. A bias voltage is applied between the front electrode group 2 and the back electrode 3 by applying an equal potential to the signal extracting electrodes 5 a and 5 b and applying a ground potential to the signal extracting electrode of the back electrode 3. . In this state, when a beam is incident on the light receiving surface, carriers (electrons and holes) are generated in the detection unit 6, and the carriers reach each strip-shaped electrode 2 a of the surface electrode group 2 as a photocurrent by a bias voltage. The current that has reached each strip-shaped electrode 2 a is output from the signal extraction electrodes 5 a and 5 b via the low-resistance diamond layer 4. At this time, the distance to the signal extraction electrodes 5a and 5b connected to both ends of the low-resistance diamond layer 4, that is, the resistance value to the signal extraction electrodes 5a and 5b differs depending on the position where the beam is incident. The current divided according to the ratio is output from the signal extraction electrodes 5a and 5b.

For example, when the current value output from the signal extraction electrode 5a is I ₁ and the current value output from the signal extraction electrode 5b is I ₂ , the carrier generated in the central portion of the detection unit 6 is a low-resistance diamond. Since it goes to both ends of the layer 4 at a ratio of 1: 1, the current value I ₁ : current value I ₂ becomes 1: 1. On the other hand, carriers generated at a position where the ratio of the distance to the end on the signal extraction electrode 5a side and the distance to the end on the signal extraction electrode 5b side is 1: 9 are both ends of the low-resistance diamond layer 4. Therefore, the current value I ₁ : current value I ₂ is 9: 1. Therefore, the difference between the current value I ₁ and the current value I _2, it is possible to estimate the position of incidence of the beam.

At this time, if the film quality of the high-resistance diamond layer 1 and the low-resistance diamond layer 4 is not uniform, variations in beam detection sensitivity (carrier generation amount) and resistance ratio occur. Therefore, in the present embodiment, the ratio of the current value I ₁ output from the signal extraction electrode 5a to the total current value I ₀ (= I ₁ + I ₂ ) output from each extraction electrode (= I ₁ / I ₀ ), or the ratio of the current value I ₂ output from the signal extraction electrode 5b to the total current value I ₀ (= I ₂ / I ₀ ), to determine the incident position of the beam. Specifically, the length of the low-resistivity diamond layer 4 and Lx, and the distance to the entrance position from the end of the signal extraction electrodes 5a side and X _A, the current value I ₁ and the current to the total current value I ₀ percentage value I ₂ is represented by the following equations 1 and 2.

Therefore, from the above Equations 1 and 2, the distance X _A is represented by the following equation 3.

Thus, in the beam position detection method of the present embodiment, determining a distance X _A using the above equation 3. Thereby, even if the film quality of the diamond layer is non-uniform and the absolute value of the total current value I ₀ which is the sum of the current values I ₁ and I ₂ output from the signal extraction electrodes 5a and 5b varies. If the incident position of the beam is the same, the ratio of the current value I ₁ and the current value I _{2 to} the total current value I ₀ does not change. Therefore, by applying this measurement method, the center position of the beam can be detected with high accuracy. can do.

  Further, the beam position monitor of the present embodiment can determine the beam incident position from the difference between the current values output from the signal extraction electrodes 5a and 5b connected to both ends of the low resistance diamond layer 4. Unlike the conventional beam position monitor, since it is not necessary to provide a large number of signal extraction electrodes and wirings, the structure can be simplified. As a result, a highly accurate beam position monitor can be manufactured at low cost. In addition, the beam position monitor of the present embodiment is excellent in durability because the detection part is formed of diamond, and can be applied to measurement of a beam having high energy such as ultraviolet rays, X-rays, and accelerated particles. it can.

  Note that the beam position monitor of the present embodiment can measure the incident position of an ultraviolet beam such as an excimer laser, an X-ray beam, or the like in addition to the emitted light, in the same manner. This broadens the practical range of beam position monitors using high-orientation diamond films and polycrystalline diamond films at low cost, opens up new fields of application, and uses ultraviolet light, vacuum ultraviolet light, and deep ultraviolet light. It can make a great contribution to the development of industrial fields.

  The effects of the embodiments of the present invention will be described below. As Example 1 of the present invention, an ultraviolet beam position monitor using a highly oriented diamond film was prepared. FIG. 5A is a plan view showing the beam position monitor according to the first embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along line AA shown in FIG. First, the low resistance silicon substrate 11 having a length of 15 mm, a width of 30 mm and a surface of (001) was exposed to a mixed plasma of methane and hydrogen to carbonize the surface. Subsequently, a bias was applied to form a diamond nucleus having an epitaxial relationship with the substrate 11. Thereafter, the bias application was stopped, and a diamond film was formed for 20 hours under the condition that the (001) plane was preferentially grown using a mixed gas of methane and hydrogen. As a result, a high-orientation diamond film 12 having a (001) surface as a high-resistance diamond layer and crystal grains arranged in a certain direction was formed on the low-resistance silicon substrate 11 with a thickness of about 20 μm.

Next, after applying a resist to the entire surface of the high-orientation diamond film 12, portions of the photoresist other than the region where the low-resistance diamond layer was formed were removed by photolithography. Next, after forming SiO ₂ on the highly oriented diamond film 12 by sputtering, the resist was removed. As a result, the highly oriented diamond film 12 was exposed only in the region where the low resistance diamond layer was formed, and the other regions were covered with SiO ₂ . Then, this sample was transferred to a reaction vessel, a mixed gas of methane and hydrogen was used as a raw material gas, diborane was further added as a doping gas, and synthesis was performed by plasma CVD for 2 hours. Thereby, the semiconductor diamond film 14 which is a low resistance diamond layer was not formed on the SiO ₂ , but was formed only on the portion where the highly oriented diamond film 12 was exposed. Thereafter, the sample was immersed in hydrofluoric acid to remove SiO ₂ to selectively form a low resistance diamond layer (semiconductor diamond film 14).

  Next, after washing with dichromic acid to remove carbon components other than diamond adhering to the surface, it was rinsed with sulfuric acid and further washed with pure water. Then, after patterning on the highly oriented diamond film 12 and the semiconductor diamond film 14 by photolithography, platinum is sputtered by a magnetron sputtering method and further lifted off, whereby the surface electrode 13 and the signal extraction electrodes 15a and 15b are formed. Formed.

  As a result, as shown in FIGS. 5A and 5B, a high-orientation diamond film 12 that is a high-resistance diamond layer is formed on the low-resistance silicon substrate 11 whose surface is the (001) plane. On the highly oriented diamond film 12, a comb-shaped semiconductor diamond film 14 and a plurality of strip-shaped electrodes 13a (surface electrodes 13) having one end engaged with the semiconductor diamond film 14 and substantially equal in width and length, A beam position monitor in which a pair of signal extraction electrodes 15a and 15b connected to both ends in the longitudinal direction of the semiconductor diamond film 14 was formed was produced. In the beam position monitor of this embodiment, the low resistance silicon substrate 11 also serves as the back electrode and its signal extraction electrode.

Next, the beam position monitor of Example 1 was irradiated with ultraviolet rays, and the relationship between the center position and the output was examined. FIG. 6 is a block diagram showing the measurement method. As shown in FIG. 6, in the measurement, an equal potential is applied to the signal extraction electrodes 15a and 15b, a ground potential is applied to the low resistance silicon substrate 11 that also serves as the signal extraction electrode, and the signal extraction electrodes 15a and 15b are applied. Resistors R1 and R2 were inserted between the _first and _second amplifier circuits, and the photocurrent output from the signal extraction electrodes 15a and 15b was measured as a voltage generated at both ends of the resistor. The obtained minute voltage was amplified by the amplifier circuit 16 and the output was input to the arithmetic circuit 17. Specifically, a pinhole is installed in front of the light receiving part of the beam position monitor, and a light source for irradiation is applied in a state where a bias voltage of 40 V is applied between the surface electrode 13 of the beam position monitor and the low resistance silicon substrate 11. Using a deuterium (L2D2) lamp (model: L7293) manufactured by Hamamatsu Photonics Co., Ltd., ultraviolet rays were irradiated to positions 0, 2, 4, 6, 8, and 10 mm from the signal extraction electrode 15a side. Outputs from the signal extraction electrodes 15a and 15b were obtained by the method shown in FIG. Note that the width of the detection portion of the beam position monitor of this embodiment, that is, the distance from the end on the signal extraction electrode 15a side to the end on the signal extraction electrode 15b side is 10 mm.

FIG. 7 is a graph showing the characteristics of the beam position monitor of this embodiment, with the horizontal axis representing the ultraviolet irradiation position and the vertical axis representing the output from each signal extraction electrode. The output from the signal extraction electrodes shown in FIG. 7 is a relative value, the total of the output current value I ₁ and the current output from the signal extraction electrodes 15b value I ₂ from the signal extraction electrodes 15a it is a ratio with respect to the current value _{I 0.} FIG. 7 also shows the calculated value of the output from the signal extraction electrode 15a. As shown in FIG. 7, as a result of the above-described evaluation, the measured value obtained by the beam position monitor of this example substantially coincided with the calculated value. Moreover, the reproducibility of the detection result was also good, and it was confirmed that the beam position can be detected with high accuracy by the beam position monitor of this embodiment.

  Next, a beam position monitor for radiation was produced as Example 2 of the present invention. FIG. 8A is a plan view showing the beam position monitor of Example 2, FIG. 8B is a plan view showing the electrode on the front surface side, and FIG. 8C shows the electrode on the back surface side. It is a top view. Since the emitted light has a high intensity, the beam position monitor of this example was produced using a polycrystalline diamond plate to prevent damage by the emitted light. Specifically, a continuous synthesis for 100 hours is performed using a mixed plasma of methane and hydrogen in the same manner as the beam position monitor of Example 1 described above, and a polycrystal having a film thickness of about 0.4 mm is formed on a silicon substrate. A diamond layer was formed. Thereafter, the silicon substrate was removed with hydrofluoric acid, and both surfaces of the remaining polycrystalline diamond layer (polycrystalline diamond plate) were polished. Next, a surface electrode group 22, a low resistance diamond layer 24, and signal extraction electrodes 25a and 25b were formed on the surface of the polycrystalline diamond plate 21 in the same manner as the beam position monitor of Example 1. Further, on the back surface of the polycrystalline diamond plate 21, a back surface electrode 23 that also serves as a signal extraction electrode was formed in a region opposite to the region where the surface electrode group 22 was formed.

  Next, when the beam position monitor of the present example was irradiated with radiated light and its characteristics were evaluated in the same manner as in Example 1, the beam position could be detected with high accuracy. Similarly, when the excimer laser was evaluated, it was possible to stably detect the beam position without damaging the monitor. In the beam position monitor of this embodiment, the signal extraction electrodes 25a and 25b on the front surface side and the signal extraction electrode (back electrode 23) on the back surface are not opposed to each other across the polycrystalline diamond plate 21. Generation of noise due to application of a bias voltage can be prevented.

It is a perspective view which shows typically the beam position monitor of embodiment of this invention. (A) is sectional drawing which shows typically the crystal grain of a highly oriented diamond film, (b) and (c) are the top views. (A) is a top view which shows the beam position monitor of the 1st modification of embodiment of this invention, (b) is a top view which shows the electrode shape. (A) is a top view which shows the beam position monitor of the 2nd modification of embodiment of this invention, (b) is a top view which shows the electrode shape. (A) is a top view which shows the beam position monitor of Example 1, (b) is sectional drawing by the AA line shown to (a). It is a block diagram which shows the output measuring method in the beam position monitor of Example 1 of this invention. It is a graph which shows the characteristic of the beam position monitor of Example 1, taking an ultraviolet irradiation position on a horizontal axis and taking the output from each electrode for signal extraction on a vertical axis. (A) is a top view which shows the beam position monitor of Example 2, (b) is a top view which shows the electrode of the surface side, (c) is a top view which shows the electrode of the back surface side. It is a perspective view which shows the conventional PSD typically. It is a disassembled perspective view which shows PSD of patent document 1. FIG. (A) is a top view which shows the structure of the synchrotron radiation position monitor of patent document 2, (b) is the sectional drawing.

Explanation of symbols

1; high resistance diamond 2, 7, 8, 13, 22; surface electrode group 2a, 13a; strip electrode 3, 23; back electrode 4, 24; low resistance diamond layer 5a, 5b, 15a, 15b, 25a, 25b 116; Signal extraction electrode 6; Detection unit 7a; Comb electrode 8a; Fishbone type electrodes 9 and 118; Substrate 10; Diamond crystal particle 11; Low resistance silicon substrate 12; Amplifier circuit 17; arithmetic circuit 21; polycrystalline diamond plate 101; diamond plate 102; hole 103; metal electrode 104; diamond electrode (conductive diamond)
110; compound semiconductor substrates 111 and 112; resistance layers 113 and 114; resistance network 115; bias electrode 117; amplifier

Claims (11)

A first diamond layer, a surface electrode group comprising a plurality of surface electrodes formed on one side of the first diamond layer and arranged in one direction, and formed on one side of the first diamond layer A second diamond layer in contact with and electrically connected to one end of each surface electrode and having a resistance lower than that of the first diamond layer and higher than that of the surface electrode; Opposite to the first and second signal extraction electrodes respectively connected to both ends in the one direction of the diamond layer and at least the surface electrode group on the other surface of the first diamond layer A bias voltage is applied between the surface electrode group and the back electrode by applying a potential to the surface electrode group via the back electrode formed in the side region and the second diamond layer. And carriers generated by a beam incident on the first diamond layer are collected by the surface electrode, and the first and second signal extraction are performed via the second diamond layer. Beam position monitor characterized by flowing separately for electrodes. 2. The beam position monitor according to claim 1, wherein the surface electrode group includes a plurality of strip-like electrodes having the same length and width and parallel to each other. The beam position monitor according to claim 1, wherein the surface electrode has a comb shape or a fishbone type. 4. The third signal extraction electrode connected to the back electrode is formed on the other surface of the first diamond layer. 5. Beam position monitor. The beam position monitor according to any one of claims 1 to 3, wherein the back electrode is a low-resistance silicon substrate, and the first diamond layer is formed on the low-resistance silicon substrate. . The beam position monitor according to any one of claims 1 to 5, wherein the first diamond layer is formed of vapor-phase synthesized polycrystalline diamond. The first diamond layer has a surface that is covered with a (001) plane, crystal grains are oriented in a uniaxial direction perpendicular to the substrate surface, and crystal orientation is also in-plane. The beam position monitor according to claim 6, wherein the beam position monitor is a diamond layer. The beam position monitor according to any one of claims 1 to 7, wherein the second diamond layer is formed of vapor-phase synthesized polycrystalline diamond. The beam position monitor according to claim 8, wherein the second diamond layer is formed of p-type semiconductor diamond to which boron is added. A surface electrode group composed of a plurality of surface electrodes formed so as to be arranged in one direction on one surface of the first diamond layer and at least the surface electrode group on the other surface of the first diamond layer are formed. Applying a bias voltage to a back electrode formed in a region opposite to the region where the surface electrode is formed, and carriers generated by a beam incident on the first diamond layer are applied to the surface electrode group by the bias voltage. Through the second diamond layer having a lower resistance than the first diamond layer and higher resistance than the surface electrode. And outputting from the first and second signal extraction electrodes respectively connected to both ends of the second diamond layer in the one direction, and outputting from the first signal extraction electrode. Beam position measurement method characterized by having the steps of determining the position of incidence of the beam on the basis of the current value I ₂ output from current value I ₁ and the second signal extraction electrodes. In the step of determining the incident position of the beam, the beam is output from the first signal extraction electrode with respect to the total current value I ₀ (= I ₁ + I ₂ ) output from the first and second signal extraction electrodes. From the ratio (I ₁ / I ₀ ) of the current value I ₁ or the ratio (I ₂ / I ₀ ) of the current value I ₂ output from the second signal extraction electrode with respect to the total current value I _{0, the} beam The beam position measuring method according to claim 10, wherein an incident position is obtained.

Images